The effect of attached tetracycline and hydrophilic groups on the enhancement of antibacterial effectiveness and low temperature flexibility of polyurethane

Tetracycline was chemically attached to polyurethane (PU) to enhance its antimicrobial activity, and a carboxyl group or polyol was also attached to PU to enhance the hydrophilicity. The attached groups affected cross‐linking, viscosity of PU solution, glass transition of soft segment, breaking tensile stress, reliable shape recovery capability, flexibility at very low temperature, surface hydrophilicity, and antibacterial effectiveness. The glass transition temperature could go up from −67.5°C for unmodified PU to −48.8°C due to the attached tetracycline. The attachment of tetracycline boosted breaking tensile stress and shape recovery by 345% and 186%, respectively, relative to unmodified PU. The attached carboxyl group and polyol improved the hydrophilicity as confirmed by water swelling and water contact angle data. Finally, PU samples with the attached tetracycline demonstrated excellent flexibility at freezing temperature compared with ordinary PU and absolutely inhibited the bacterial growth of S. aureus and K. pneumoniae on PU.